Projects per year
Abstract
Smoking is strongly associated with schizophrenia. Although it has been widely assumed that this reflects self-medication, recent studies suggest that smoking may be a risk factor for schizophrenia. We performed a two-sample bi-directional Mendelian randomisation study using summary level genomewide association data from the Tobacco and Genetics Consortium and Psychiatric Genomics Consortium. Variants associated with smoking initiation and schizophrenia were combined using an inverse-variance weight fixed-effects approach. We found evidence consistent with a causal effect of smoking initiation on schizophrenia risk (OR 1.71, 95% CI 1.30, 2.25, p<0.001). However, after relaxing the p-value threshold to include variants from more than one gene and minimize the potential impact of pleiotropy, the association was attenuated (OR 1.03, 95% CI 0.97, 1.09, p=0.32). There was little evidence in support of a causal effect of schizophrenia on smoking initiation (OR 1.01, 95%CI 0.98-1.04, p=0.32). MR Egger regression sensitivity analysis indicated no evidence for pleiotropy in the effect of schizophrenia on smoking initiation (intercept OR 1.01, 95%CI 0.99-1.02, p=0.49). Our findings provide little evidence of a causal association between smoking initiation and schizophrenia, in either direction. However, we cannot rule out a causal effect of smoking on schizophrenia (or vice versa) related to heavier, lifetime exposure, rather than initiation.
Original language | English |
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Article number | 40653 |
Number of pages | 8 |
Journal | Scientific Reports |
Volume | 7 |
DOIs | |
Publication status | Published - 19 Jan 2017 |
Research Groups and Themes
- Brain and Behaviour
- Tobacco and Alcohol
Keywords
- smoking
- schizophrenia
- genetics
- Mendelian randomization
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Dive into the research topics of 'Investigating causality in associations between smoking initiation and schizophrenia using Mendelian randomization'. Together they form a unique fingerprint.Projects
- 3 Finished
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MRC UoB UNITE Unit - Programme 6
Munafo, M. R. (Principal Investigator) & Munafo, M. R. (Principal Investigator)
1/06/13 → 31/03/18
Project: Research
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MRC UoB UNITE Unit - Programme 1
Davey Smith, G. (Principal Investigator)
1/06/13 → 31/03/18
Project: Research
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MRC UoB UNITE Unit - programme 3
Timpson, N. J. (Principal Investigator) & Timpson, N. J. (Principal Investigator)
1/06/13 → 31/03/18
Project: Research